/*
 * Copyright (C) 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.gson;

import java.util.Map;
import java.util.Set;

import com.google.gson.internal.LinkedTreeMap;

/**
 * A class representing an object type in Json. An object consists of name-value pairs where names
 * are strings, and values are any other type of {@link JsonElement}. This allows for a creating a
 * tree of JsonElements. The member elements of this object are maintained in order they were added.
 *
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
public final class JsonObject extends JsonElement {
    private final LinkedTreeMap<String, JsonElement> members =
            new LinkedTreeMap<String, JsonElement>();

    @Override
    JsonObject deepCopy() {
        JsonObject result = new JsonObject();
        for (Map.Entry<String, JsonElement> entry : members.entrySet()) {
            result.add(entry.getKey(), entry.getValue().deepCopy());
        }
        return result;
    }

    /**
     * Adds a member, which is a name-value pair, to self. The name must be a String, but the value
     * can be an arbitrary JsonElement, thereby allowing you to build a full tree of JsonElements
     * rooted at this node.
     *
     * @param property name of the member.
     * @param value    the member object.
     */
    public void add(String property, JsonElement value) {
        if (value == null) {
            value = JsonNull.INSTANCE;
        }
        members.put(property, value);
    }

    /**
     * Removes the {@code property} from this {@link JsonObject}.
     *
     * @param property name of the member that should be removed.
     * @return the {@link JsonElement} object that is being removed.
     * @since 1.3
     */
    public JsonElement remove(String property) {
        return members.remove(property);
    }

    /**
     * Convenience method to add a primitive member. The specified value is converted to a
     * JsonPrimitive of String.
     *
     * @param property name of the member.
     * @param value    the string value associated with the member.
     */
    public void addProperty(String property, String value) {
        add(property, createJsonElement(value));
    }

    /**
     * Convenience method to add a primitive member. The specified value is converted to a
     * JsonPrimitive of Number.
     *
     * @param property name of the member.
     * @param value    the number value associated with the member.
     */
    public void addProperty(String property, Number value) {
        add(property, createJsonElement(value));
    }

    /**
     * Convenience method to add a boolean member. The specified value is converted to a
     * JsonPrimitive of Boolean.
     *
     * @param property name of the member.
     * @param value    the number value associated with the member.
     */
    public void addProperty(String property, Boolean value) {
        add(property, createJsonElement(value));
    }

    /**
     * Convenience method to add a char member. The specified value is converted to a
     * JsonPrimitive of Character.
     *
     * @param property name of the member.
     * @param value    the number value associated with the member.
     */
    public void addProperty(String property, Character value) {
        add(property, createJsonElement(value));
    }

    /**
     * Creates the proper {@link JsonElement} object from the given {@code value} object.
     *
     * @param value the object to generate the {@link JsonElement} for
     * @return a {@link JsonPrimitive} if the {@code value} is not null, otherwise a {@link JsonNull}
     */
    private JsonElement createJsonElement(Object value) {
        return value == null ? JsonNull.INSTANCE : new JsonPrimitive(value);
    }

    /**
     * Returns a set of members of this object. The set is ordered, and the order is in which the
     * elements were added.
     *
     * @return a set of members of this object.
     */
    public Set<Map.Entry<String, JsonElement>> entrySet() {
        return members.entrySet();
    }

    /**
     * Returns the number of key/value pairs in the object.
     *
     * @return the number of key/value pairs in the object.
     */
    public int size() {
        return members.size();
    }

    /**
     * Convenience method to check if a member with the specified name is present in this object.
     *
     * @param memberName name of the member that is being checked for presence.
     * @return true if there is a member with the specified name, false otherwise.
     */
    public boolean has(String memberName) {
        return members.containsKey(memberName);
    }

    /**
     * Returns the member with the specified name.
     *
     * @param memberName name of the member that is being requested.
     * @return the member matching the name. Null if no such member exists.
     */
    public JsonElement get(String memberName) {
        return members.get(memberName);
    }

    /**
     * Convenience method to get the specified member as a JsonPrimitive element.
     *
     * @param memberName name of the member being requested.
     * @return the JsonPrimitive corresponding to the specified member.
     */
    public JsonPrimitive getAsJsonPrimitive(String memberName) {
        return (JsonPrimitive) members.get(memberName);
    }

    /**
     * Convenience method to get the specified member as a JsonArray.
     *
     * @param memberName name of the member being requested.
     * @return the JsonArray corresponding to the specified member.
     */
    public JsonArray getAsJsonArray(String memberName) {
        return (JsonArray) members.get(memberName);
    }

    /**
     * Convenience method to get the specified member as a JsonObject.
     *
     * @param memberName name of the member being requested.
     * @return the JsonObject corresponding to the specified member.
     */
    public JsonObject getAsJsonObject(String memberName) {
        return (JsonObject) members.get(memberName);
    }

    @Override
    public boolean equals(Object o) {
        return (o == this) || (o instanceof JsonObject
                && ((JsonObject) o).members.equals(members));
    }

    @Override
    public int hashCode() {
        return members.hashCode();
    }
}
